Process for the production of improved heating oils



M. C. K. JONES PROCESS FOR THE PRODUCTION OF IMPROVED HEATING OILS,

Filed May 13, 1952 March 1, 1955 2 Sheets-Sheet l .mzoN rwmkmmm March 1, 1955 M. C. K. JONES 2,703,307

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GCE 0160.615

United States Patent Oiice 2,703,307 Patented Mar. 1, 1955 `PROCESS FOR THE PRODUCTION OF IMPROVED HEATING OILS Minor C. K. Jones, Mountainside, N. J., assignor to Esso Research and Engineering Company, a corporation of Delaware Application May 13, 1952, Serial No. 287,526

3 Claims. (Cl. 196-41) The present invention is concerned with an improved process for the production of high quality heating oils. In accordance with the present process heating oils containing nely divided sediment are rendered suitable for burning in burning equipment by homogenizing the oil.

The present invention is broadly concerned with the production of improved hydrocarbon mixtures known as, heating oils, of the nature employed in various burner systems as domestic and industrial heating oils. Heating oils may be derived from petroleum by a variety of methods including straight distillation from crude petroleum oil, and thermal or catalytic cracking of various petroleum oil fractions. Heretofore, in the art, heating oil blends comprised a relatively large proportion of virgin heating oil as compared to cracked heating oils. However, due to the desirability of virgin heating oils as feed stocks to various cracking operations, as for example, a iiuid catalytic cracking operation, the blends comprise an increasing proportion of cracked heating oil fractions as compared to virgin stocks. Virgin heating oil fractions are also very desirable as diesel oil products which further decreases their availability for heating oil blends. It is known in the art that yheating oils consisting completely or in part of certain catalytic cracked stocks are characterized by an undesirable instability giving rise to the formation of sediment. cracked heating oils are blended with sweetened virgin heating oils, certain undesirable characteristics are increased due to their incompatibility. As a result, such blended fuel oils tend to cause clogging of filters, orifices, or conduits associated with the burning systems in which Ithey are employed.

It is also well known in the art that heating oils, when stored for prolonged periods, are very prone to form carbonaceous sediment. This is particularly true for those heating oils which contain cracked stocks.

Little is known as yet concerning the actual mechanisms by which sediment is formed in a heating oil. It -does appear, however, that the smallest unit particles are in the micron range, i. e., in the order of 5 microns or less. It further appears that these unit particles agglomerate or otherwise become large enough to plug the minute passageways and orifices present in an oil burner. The exact size of particles that are capable of plugging `a burner is diicult to determine for several reasons. First, the critical size will vary with both the type and size of a burner. Second, it will depend to a great extent on the physical condition of any given burner in that a clean burner will whose internal parts are coated with varnish or other si-milar deposits. Third, the very problem of determining the'I sizes of sediment particles that exist 1n an oil is an eX-f tremely diflicult one.

In view of the factors just mentioned, empirical test procedures have been developed and correlated with actual. field results to evaluate the plugging tendencies of a heating oil. Tests of this type have proved to be very satisfactory in this respect. It is such a test, to be described hereinafter, that has demonstrated the effectiveness iof the present invention.

In order to improve the quality of blended heating oils, various processes have been practiced in the art. It is known in the art to process a virgin heating oil by a caustic wash if the oil be relatively sweet. On the other hand, if the virgin heating oil hasa relatively high mercaptan content, the oil is processed by a doctor treat or an`equivalent sweetening. operation. On the other hand,l i

It is also known that when L plug less readily than a burner light cracked heating oils in many operations merely require a caustic wash. However, the conventional procedure is to secure the cracked heating oil from a relatively severe cracking operation in which case it is necessary to acid treat the cracked heating oil followed by a caustic wash in order to control the carbon residue. This latter operation is not desirable since acid treatment polymerizes many desirable constituents resulting in a loss in yield. Furthermore, the sludge is expensive and difficult to handle.

-In accordance with the present invention, the solid particles comprising sediment in domestic heating oils are rendered innocuous with respect to their ability to plug screens, lters and burner nozzles, by passing the oil through a homogenizer. The oil is forced through the extremely small openings of a conical valve with a pressure of 1000 to 8000 lbs. per sq. in., preferably at a pressure in the range from 3,000 p. s. i. to 5,000 p. s. i. The shearing stress induced reduces the particle size from upwards of 2 or 3 microns in diameter to less than-0.3 micron. Heating oils and heating oil blends which may be processed in accordance with the present invention are particularly hydrocarbon mixtures of which more than about 10%, preferably from about 15% to 60% by volume consist of stocks derived from cracking operations. More precisely still, the finished blends may be characterized as petroleum fractions containing a proportion of cracked stocks greater than 10%, preferably from about 15% to 60% by volume, and falling within A. S. T. M. specification D-396-48T for fuel oils (Grades No. l or 2). Inspections of a typical heating oil blend are for ex-ample:

Gravity, API 34.5 Distillation, A. S. T. M.:

Initial, B. P. "F 363 10% at 7F 438 50% at "F 504 at F 583 Final, B. P. F 640 Flash, F 158 Color, Tag Robinson 15 Viscosity, SSU/lOO" F 34.7 Pour point, F 0 Sulfur, weight per cent .37 Suspended solids, mgs./ ml 1.0 Carbon residue on 10% residuum, .08 Corrosion, 1 hr. at 212 F Pass Diesel index 48.2 Aniline point, "F

An object of the present invention is to reduce the plugging tendencies of heating oils by homogenization. Accordingly, an oil that has developed undesirable sediment in storage is passed through a homogenizer such as a colloid mill or a valve of a type to be described hereinafter. The oil may be withdrawn from the storage tank or vessel, passed through the homogenizer and then returned to the same or a different tank. Alternatively, a homogenizing device may be placed directly within the vessel and the oil homogenized by circulating it through the device.

A second object of the present invention is to provide a process by which heating oils of low plugging tendencies lmay be produced. These and other objects will become apparent in the ensuing description.

The present invention may be more fully understood by reference to the attached drawings in which:

Figure l illustrates a method for producing homogenized heating oils, and

Figure 2 illustrates a homogenizing valve.

Referring speciiically to Figure l, a crude oil feed stock is introduced into distillation zone 1 by means of line 2. Temperature and pressure conditions in zone 1 are adapted to remove overhead by means of line 3 normally gaseous hydrocarbons and to remove by means of line 4 hydrocarbon constituents boiling in the motor fuel and naphtha boiling ranges. A virgin heating oil fraction is removed from zone 1 by means of line S while a gas oil fraction is removed by means of line 6. A residuum fraction comprising the higher boiling constituents is removed as a bottoms by means of line 7.

The virgin heating oil fraction removed by meaans of line 5 may be treated by various processes in order to refine the same. Normally this fraction is treated with a mild caustic wash, as for example sodium hydroxide in treating 'zone 8. The fresh caustic is introduced by means of line `9 While the vspent caustic is removed 'by means of line 10.

The caustic treated virgin heating oil is removed by means of line 11 land sweetened if necessary by the removal of rnercaptans in sweetening zone 12. The sweetening agent is introduced by means of line 13 while the spent sweetening agent is removed by means of line 14. Any suitable sweetening agent or process may be utilized as for example a doctor treat, a bauxite treat or by a Unisol process. The finished virgin heating oil is removed by means of line 1S and blended with cracked heating oil produced as hereinafter described.

It is to be understood that distillation zone 1, treating zone l8 and sweetening zone 12 may comprise Iany suitable number and arrangement of stages. fraction removed by means :of line 6 is passed to cracking zone 1'6 which may comprise any suitable cracking operation, as for example, a thermal or a catalytic cracking process. However, the present invention is particularly directed toward the production of a high 'quality virgin-cracked heating oil blend wherein the cracking process comprises a catalytic cracking operation, as for example a liuid catalytic cracking operation.

A fluid catalytic cracking plant is composed of three sections: cracking, regeneration, and fractionation. The cracking reaction takes place continuously in one reactor at a temperature in the range from about 800 F. to l050 F. The spent catalyst is removed continuously for regeneration in a separate vessel, from which it is returned to the 'cracking vessel, which is at a pressure below about 200 lbs. usually below about 50 lbs. per sq. in. Continuity of ow of catalyst as well as of oil is thus accomplished, and the characteristic features of fixedbed designs involving the intermittent shifting of reactors through cracking, purging, and regeneration cycles are eliminated.

Regenerated catalyst is withdrawn from the regenerator and flows by gravity down a standpipe, wherein a sufficiently high pressure head is built up on the catalyst to allow its injection into the fresh liquid oil stream. The resulting mixture of oil and catalyst flows into the reaction vessel, in which gas velocity is intentionally low, so that a high concentration of catalyst will result. The cracking that takes place results in carbon deposition on the catalyst, requiring regeneration of the catalyst. The cracked product oil vapors are withdrawn from the top of the reactor after passing through cyclone separators to free them of any entrained catalyst particles, While the spent catalyst yis withdrawn from the bottom of the reactor and is injected into a stream of undiluted air 1 which carries the catalyst into the regeneration vessel. The products of combustion resulting from the regeneration of the catalyst leave the top of this vessel and pass through a series of cyclones where the bulk of the entrained catalyst is recovered. The regenerated catalyst is withdrawn from the bottom of the vessel to complete its cycle.

The cracked products are removed from cracking zone 16 (overhead from the reactor) by means of line 28 and introduced into a distillation zone 29. Temperature and pressure conditions in zone 29 are adjusted to remove overhead by means of line 30 normally gaseous constituents and to remove by means of line 31 hydrocarbon constituents boiling in the motor fuel boiling range. fraction boiling above the heating oil boiling range is removed as a bottoms fraction by means of line 32. A fraction boiling in the heating oil boiling range is removed by means of line 33 and in accordance with the present invention may be caustic 'washed in zone 21. The fresh caustic or other treating agent is introduced by means of line 22 while the spent treating agent is removed by means of line 23.

In accordance with the present invention, the caustic washed ycracked heating oil which ows from zone 21 through line is homogenized in zone 24. The homogenized oil is withdrawn from zone 24 by means of line 27 and preferably blended with the virgin heating oil secured as hereinbefore described in line 15.

While the invention has been described with respect to homogenizing only the cracked heating oil prior to The gas oil u blending, it is to be understood that under certain conditions the virgin and cracked heating oils may be blended by means of line 28 and the entire blend homogenized.

Any suitable method of homogenizing may be utilized. However, it is desirable that the micron size of the suspended particles be reduced to below 0.5 micron preferably to a micron size in the range from 0.1 to 0.3. Pressures should be in the range from 1,000 to v8,000 lbs. per sq. in., preferably in the range from 3,000 to 5,000 p. s. 1.

A very desirable type of homogenizing valve is illustrated in Figure 2. This valve 43 consists of a block 44 having a bore 45 connecting with a venturi 46. A conical seat 47 is provided at the lower end of the bore and a valve stern 48 movably arranged in block 44. The valve stem 48 is provided with adjustment wheel 49 and a head 50 adapted to operate in bore 4S and co-act with valve seat 47 to form a point of shearing stress.

Heating oil introduced `through line 41 and venturi 46 passes the point -of shearing in the bore 4S' and is withdrawn through line 51 and passed to any desired location.

A high pressure pumping device is preferably used in conjunction with the homogenizing valve just ldescribed to generate the shearing forces required for homogenization. It "is apparent that apparatus -of vthis character may be readily employed in homogenizing heating oil stored in tanks as well as heating oil in various refinery streams.

The present invention may be more fully understood by the following example illust-rating the same:

EXAMPLE An oil having a high content of suspended solids (3 mg. or better per ml.) was pumped through a filter. After feeding 8.8 liters of the oil through the filter, the run was stopped because of plugging as indicated by the high pressure differential which developed across the filter (66.6 cm. HgAP). The total Weight of sediment collected on the filter after feeding the 8.8 liters of oil was 44.6 mg. At this rate, feeding 12 liters of the oil would have resulted in about 61 mg. of sediment.

For the second run, similar oil with a like amount of sediment was homogenized twice-through at 4,000 p. s. i. in a Gaulin 2 stage homogenizer, manufactured and sold by the Manton-Gaulin Manufacturing Company, Everett, Massachusetts. Actually the suspended sediment after homogenization was 3.3 mg./ 100 ml. This run was made feeding 12 liters of stock and resulted in a final pressure differential of 40.1 cm. Hg; the weight of sediment collected on the filter pad was 41.1 mg. These results of sediment weight and pressure differential are indicative of non-plugging performance in actual oil burners. The following table lists pertinent data taken during the two operations.

Filter-plugging tendency of a heating ail1 as affected by homogenization Before homogeniza- After homogenization tion Vol. oil plmp through .an f .alla g minutes g minutes 0. 7 0 O. 3 0 13. 4 18 1. '2 17 3B 2.1 34 31. 6 6D 5. 4 51 37. 8 74 9. 1 67 37. 9 90 12. 7 85 36. 4 108 16. 4 102 35. 8 125 18. 6 118 44. 3 141 21. 7 135 66. 6 150 25. 7 151 29. 9 167 35. 3 184 40. 1 200 1 Containing about 3.3 mg. suspended solids per 100 ml. 2 Plugged.

What is claimed is:

1. A method of producing a heating oil that will not plug conventional oil burners which comprises fractionating a petroleum crude oil to form a plurality of fractions including a fraction boiling yin the heating oil range and a fraction boiling in the gas oil range, caustic washing the heating-oil fraction, sweetening the caustic washedv heating oil fraction to form a sweetened heating oil, cracking the gas oil fraction, fractionating the cracked products to form a plurality of fractions including a cracked fraction boiling in the heating oil range, caustic washing the cracked heating oil, homogenizing the caustic-washed cracked heating oil by forcing it through a small opening under a shearing pressure of 1,000 to 8,000 p. s. i., and blending said sweetened heating oil and said caustic-washed cracked heating oil.

2. A method of producing a heating oil that will not plug conventional oil burners which comprises fractionating a petroleum crude oil to form a plurality of fractions including a fraction boiling in the heating oil range and a fraction boiling in the gas oil range, caustic washing the heating oil fraction, sweetening the caustic washed heating oil fraction to form a sweetened heating oil, cracking the gas oil fraction and fractionating the cracked products therefrom to form a plurality of fractions in- 6 cluding a fraction boiling in the heating oil range, blending said sweetened heating oil and said cracked heating oil fractions, and homogenizing the resulting blend by forcing it through a small opening under a shearing pressure of 1,000 to 8,000 p. s. i.

3. A method as defined in claim 2 in which the cracked heating oil is caustic washed before being blended with the sweetened heating oil.

References Cited in the le of this patent UNITED STATES PATENTS 2,420,544 Jones May 13, 1947 2,592,383 Blatz Apr. 8, 1952 FOREIGN PATENTS 591,743 France Apr. 16, 1925 

1. A METHOD OF PRODUCING A HEATING OIL THAT WILL NOT PLUG CONVENTIONAL OIL BURNERS WHICH COMPRISES FRACTIONATING A PETROLEUM CRUDE OIL TO FORM A PLURALITY OF FRACTIONS INCLUDING A FRACTION BOILING IN THE HEATING OIL RANGE AND A FRACTION BOILING IN THE GAS OIL RANGE, CAUSTIC WASHING THE HEATING OIL FRACTION, SWEETENING THE CAUSTIC WASHED HEATING OIL FRACTION TO FORM A SWEETENED HEATING OIL, CRACKING THE GAS OIL FRACTION, FRACTIONATING THE CRACKED PRODUCTS TO FORM A PLURALITY OF FRACTIONS INCLUDING A CRACKED FRACTION BOILING IN THE HEATING OIL RANGE, CAUSTIC WASHING THE CRACKED HEATING OIL, HOMOGENIZING THE CAUSTIC-WASHED CRACKED HEATING OIL BY FORCING IT THROUGH A SMALL OPENING UNDER A SHEARING PRESSURE OF 1,000 TO 8,000 P.S.I., AND BLENDING SAID SWEETENED HEATING OIL AND SAID CAUSTIC-WASHED CRACKED HEATING OIL. 